Noncollapsible tubing



March 6, 1945'. FOGG 2,371,042

NONCOLLAPSIBLE TUBING Filed Jan. 16, 1945 I iuI-IIILII-lhluuuul-luuuuuuuuuuuuuuuuuuuul-l w INVENTOR W ATTORNEY than the tube.

Patented Mar. 6, 1945 UNITED STATES PAT EN T OFFICE" NON COLLAPSIBLEF TUBING Robert E, Fogg, Wilmington," Del., assignor, to-

E. I. du Pont de Nemours& Company, Wilmin ton, .Del. ,.acorporation of llelaware. V 7 Application January 16, 1943; 'Serial'No. 472,613 7 Claims. (ci."1'3s 5.c)

This invention relates to a non-collapsible fabric ventilating tube, such as thatcommonly used in ventilating mines, ship holds, tunnels,

and" the like.

consisted'of the insertion'of a long spiral spring having a relaxed diameter of somewhat more The spring was inserted into the tubeby twisting which reduced its diameter and 'when in place was allowed to expand, thereby expanding the tube. Such a device was not'satisfactory since the springs were large and cumbersome and very inconvenient to-hand1e. Another device consisted essentially of metal hoops around the tube, the fabric andthe metal being riveted together. This construction likewise was not en- 'tirely satisfactory since the tube 'could not be folded into a manageable package.

Itis therefore an object of this invention to provide a flexible fabric ventilating tube which can be'used in circulating air under a vacuum. without any appreciable collapse of the wallsof' the -tube.-

Another object'of this invention is the provisionof a flexible'ventilating tube which can be rolled or festooned intoa small convenient pack...

Other objects will'appear as the description of the invention proceeds.

These and other objects are accomplished by preparing a laminated fabric which is impermeable to air by cementing two layers of the fabric together. Before the two cemented sides are placed in contact, however, strips of spring steel are inserted transversely between the laminations, and the assembly is passed through a calender or other means which brings the cemented surfaces together under pressure so that the flexible steel members are embedded in the cement between the two layers of fabric. A coupling means, such as a slide fastener, is then attached to each longitudinal edge. The fabric is then cut off at suitable lengths and the two parts of the slide fastener are brought together by rolling up the fabric into a long cylinder. Means are provided at each end of the cylinder for'joining it to other similar tubes when put in use. The tube may be disassembled by running back the slide fastener. When this is done the springs straightf as .035 inchor even thicker.

ally about /2' inch wide although with small tubes en out and thefabric again" lies flatandmay be readily rolledorfestooned into a small package. The invention willbe more readily understood -from-the drawing in which Figure I is a side elevation of the tube in use. Figure II is a section alongthe'lines II-IIof Figure I. Figu're III is a plan View ofthe tube laid flat. Figure IV is a diagrammatic view partly in section showing a layout of the parts immediately before the fabrics are cemented together. Figure V shows an-alternate means of joining the longitudinal'edges of the fabric.

In all of the figures, I represents the fabric which may be of any type of weave having suffiternate arrangement of fastening the longitudinal edges is shown as a metallic clasp made up ofinterlocking members 6 and I.

The spring steel strips are usually about .020

to .025 inch in thickness and are preferably made from a relatively high carbon steel having a Rockwell hardness of 55 in the case of small tubes of -3 or 4 inches in diameter. This thickness may be less, but rarely less than .010 inch in thickness. On. the other hand whenthe diameter of the tube is very large, that is, a matter of feet in diameter, the spring steelmay have a thickness of as high The strips are usuinch is sufficient and in the case of large tubes,

they may be inch or more. The steel reinforcing members are usually spaced about 6 inches apart for an 8 inch tube. For some uses this distance may be more or less but usually they should not be spaced more than 8 inches or less than 4 inches for an 8 inch tube. The spacing will be correspondingly more or less for larger or smaller tubes as will be apparent.

In lace of cementing the steel strips between two layers of fabric, they may be secured in place by cementing or stitching fabric flaps over sufllcient area to prevent them from coming out. One convenient way of doing this is to form a This construction has the advantage that they may be readily replaced merely by bending them in the middle when the fabric is lying flat and withdrawing the ends from the pockets. In place of steel, other spring metals may be used, such as brass, although steel is preferred. Under some conditions it is desirable to use plastic strips in place of the steel spring. When such a substitution is made, the dimensions given above do not hold. When such plastics are used, they may be inserted as described above or may be cemented to the fabric.

The steel or plastic reinforcing members are preferably inserted between the fabric layers at an acute angle to the edge of the fabric as shown in the drawing. This method of manufacture results in a tube which has in effect a helical reinforcing member which is preferable to a plurality of reinforcing hoops disposed at right angles to the axis of the tube. The preferred arrangement of the reinforcing members is to place them at such an angle and at such a distance apart that when they are bent in the form of a tube, one end substantially abuts the opposite end of the adjacent reinforcing member at the slide fastener.

The ventilating tube prepared according to the present invention offers many advantages not found in the prior art. One of the primary advantages is that the tube does not collapse under any vacuum which would normally be used in a ventilating system of this type. A further advantage is that the sags between the reinforcing members are very slight and therefore the effective diameter of the tube is not materially reduced when subjected to a vacuum. This results in much less internal friction in the tube. In the prior art construction particularly where the reinforcing members are hoops disposed at right angles to the axis of the tube at fixed distances, the fabric between the reinforcing members sags and thereby not only reduces the effective internal diameter of the tube but shortens the length of the tube due to the sags. These difficulties are avoided in the present invention. Another advantage is that the tube may be prepared in continuous lengths of substantially any magnitude desired. A still further advantage is that the tube may be disassembled and packed'in a small package. Recently many advancements have been made in coating fabrics to render them tough and at the same time retaining their resilience. With the proper selection of fabric, tubes may be prepared which are very light and lengths may be carried by one man which heretofore required several men. There is no limitation placed on the kind and weight of fabric which may be used other than that it must be sufficiently strong and airtight to serve the purpose for which itis intended. There is also no limitation on the cement used to laminate the fabrics although cellulose derivative and resin oements are preferred due to their water-proof character. Likewise the fabrics may be coated with cellulose derivatives or resins of various types, among these may be mentioned vinyl resins, including polyvinyl acetals, copolymers of vinyl chloride and vinyl acetate, the acrylate resins and the methacrylate resins. The rubberized fabrics commonly used in the prior art are also satisfactory.

It is apparent that many widely different embodiments of this invention may be made without departing from the spirit and scope thereof, and therefore, it is not intended to be limited except as indicated in the appended claims.

I claim:

1. A flexible ventilating tube comprising an airtight fabric and firmly attached thereto fiat spaced transversely disposed reinforcing spring members having a length substantially equal to the circumference of the tube.

2. The article of claim 1 in which the reinforcing members are spring steel.

3. The article of claim 1 in which the reinforcing members are disposed atan acute angle to the axis of the tube thereby forming a segmented helix.

6. The article of claim 5 in which the readily detachable seam is a slide fastener.

'7. A ventilating tube comprising a plurality of fabric layers joined together by means of a cement and having embedded in the said cement steel reinforcing members having a thickness between about .020 and .035 in., and a width of the order of A; to of an inch and spaced about 4 to 8 in., apart, said reinforcing members being slightly less inlength than the circumference of the tube and readily detachable means extending longitudinally along the tube whereby the said tube may be opened and the reinforced fabric material laid flat.

ROBERT E. FOGG. 

